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NMO34 with the W640 (64" whip) vs NMO-27 vs CWB-27

niceguy71

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Ah, OK.

So the extra 6" didn't lower the resonance point enough to solve the issue. Since the spring is only 2 1/4", that's not going to solve the issue on it's own.

Easy answer #1:
Switch to the NMO30 coil.

Easy answer #2:
Cut your losses on the NMO-34 coil and just buy the NMO-27 coil. Whip length for that is probably closer to 47 inches, if I recall correctly.

Hard answer #1:
Find a 75" long whip that'll fit the NMO mount cone adapter. (I said it was hard….)
I am trying to get all my antenna's SWR set up for my "Great Antenna Test of 2025" video... I wanted to put this in the test....

anyway I'm going to buy the NMO27 asap ..... is this the one I want ( I want the all black one)... but I want to make sure to get the right one.....
I get free shipping on Amazon so if I can get the whip with it for free shipping I'll go that route...

so before I order one mmckenna is this the NMO27 you like? Amazon NMO27 say's Larsen STRINGS??? I want to make sure I don't get a knock off.

thank you in advance.
 

mmckenna

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That looks correct. I'm wary of random Amazon sellers, though.

$58 at Digikey:

$59 at Arcadian:
 

niceguy71

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That looks correct. I'm wary of random Amazon sellers, though.

$58 at Digikey:

$59 at Arcadian:
thank you.... I tried to order from Arcadian.. but you have to buy a minimum of 9 units..... ...I just need one.

on Digikey it only say's pulse... most of the ones I look at say Larsen on the top, on one side and NMO 27 on the top of the other side

again thank you
 

slowmover

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I took some #14 AWG copper and wrapped it around the antenna with 6 inches past the top..... it did bring down the SWR ...but not enough???
will a spring fix this?..... any other fixes?

I also put my ohm meter to the center pin and the whip... and got all Zero's..... so the NMO is contacting the magnetic base just fine.

I think I'm out $213 bucks... and still need to buy my friend a Larsen NMO27 for at least another $100 bucks.

I know people have been talking about this great set up for a year now..... but I thought someone had actually done it and made it work??? perhaps it was all in theory and I thought it was a fact.

There’s experiments to try to alter capacitance and lower SWR. Though I’d now use an NMO30.

IMG_8321.jpeg
 

niceguy71

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There’s experiments to try to alter capacitance and lower SWR. Though I’d now use an NMO30.

View attachment 187506
no thanks, I'll stick to proven products from now on....... this group has always been fantastic in helping me with any of my projects.... if the guys here tell me something... I generally swear by it.....
but sorry to say I'm going to break the 5 foot minimum antenna recommendation and get the 49 inch NMO27.... hope I don't poke my eye out with that little thing.... I may come back and say I made another mistake with a less than 5 foot antenna.... but I think it will be fine for the Jeep..... I'm just hoping it will work as good as the Stryker SR-A10.
we drove down a trail the other day and I was a bit concerned about the Stryker on the hood... but it's never moved one bit and that whip has just about bent over completely.... heck of a magnet I guess.
 

mmckenna

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K9KLC

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I'm just hoping it will work as good as the Stryker SR-A10.
Isn't this (the Larsen) almost 20 inches shorter than the Stryker? I'm not totally sure I'd look for "as good" but you never know. Good Luck! Let us know how it turns out. Might be better for use on the Jeep being a little shorter anyway.
 

N4GEX

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Here is the SWR curve of my Larsen NMO30 coil, 64" whip, and mag mount mounted on the roof of my truck cab:
IMG_2494.jpg

I'm not using a spring, but if I add one it just shifts the curve to the left a bit. I'm going to be installing a permanent hole-mount NMO base soon, so maybe that'll shift the curve down a bit.
 

K9KLC

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Here is the SWR curve of my Larsen NMO30 coil, 64" whip, and mag mount mounted on the roof of my truck cab:
View attachment 187515

I'm not using a spring, but if I add one it just shifts the curve to the left a bit. I'm going to be installing a permanent hole-mount NMO base soon, so maybe that'll shift the curve down a bit.
Thanks this is what I needed to see. Is the 64" uncut and pulled out the end or ??
 

K9KLC

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When is someone going to get and test a President Colorado wide band antenna? It’s 54” tall and covers about 21 to 30MHz, might be a replacement for the CWB27. Any nice guys out there wanna volunteer?

I'd need to not only try that but cut it open too to see what's happening in there. Expensive mission. I'm always cautious when things seem like they're too good to be true.

I've for a dummy load that's 1:1 "ish" from 1.8 MHz to 927 MHz that we've used it on so far but, it doesn't get out too well...
 

niceguy71

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When is someone going to get and test a President Colorado wide band antenna? It’s 54” tall and covers about 21 to 30MHz, might be a replacement for the CWB27. Any nice guys out there wanna volunteer?

not me.... I just spent another $200 bucks buying a couple things to finish the Jeep ( NMO27 for one)
I'd like to someday try a laird antenna c27 as they say it's as good as a 102" Stainless Steel Whip ( Yeah Right)

read the description the 53 inch tall antenna that works like a 102" whip
 

prcguy

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not me.... I just spent another $200 bucks buying a couple things to finish the Jeep ( NMO27 for one)
I'd like to someday try a laird antenna c27 as they say it's as good as a 102" Stainless Steel Whip ( Yeah Right)

read the description the 53 inch tall antenna that works like a 102" whip
As you can imagine, that ad is a complete lie. I think the C27 can hold its own among similar size antennas but not a fulll size 1/4 wave.
BTW, you are not done spending, just give in to that.
 
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